Currently, ITU-R (International Telecommunication Union-Radio communication sector) has established IMT (International Mobile Telecommunication)-Advanced scheme. In 3GPP (3rd Generation Partnership Project), LTE-Advanced (LTE-A) of improving a system performance has been standardized while maintaining backward compatibility with Rel. 8 LTE (Release 8 Long Term Evolution).
In RAN1, coordinated multi-point transmission and reception (CoMP) of controlling a transmission power or a transmission base station between multiple base stations based on a change in an instantaneous interference power has been examined only for the LTE-A. Further, a pilot signal (CSI-RS: Channel State Information-Reference Signal) for estimating downstream space information has been examined to realize the CoMP. The transmission base station that supports the CoMP is assumed to transmit the CSI-RS.
FIG. 22 is a diagram illustrating an exemplary pattern (R1-101676), which is a simulation assumption agreed in RAN1 #60, when up to three cells can be multiplexed with four antenna ports. In FIG. 22, the vertical axis represents a frequency and the horizontal axis represents a time. Further, one sub-frame is formed by fourteen OFDM symbols of OFDM symbols #0 to #13 shown along the horizontal axis. In the exemplary pattern shown in FIG. 22, the CSI-RS is transmitted with OFDM symbol #10 (see NPL 1).
FIGS. 23 to 27 are diagrams illustrating a plurality of exemplary patterns when up to five cells can be multiplexed with eight antenna ports. The exemplary patterns shown in FIGS. 23 to 27 are exemplary patterns slightly corrected from exemplary patterns (R1-100498) (see NPL 2). In FIGS. 23 to 27, the vertical axis represents a frequency and the horizontal axis represents a time. Further, one sub-frame is formed by fourteen OFDM symbols of OFDM symbols #0 to #13 shown along the horizontal axis. In regard to regions partitioning the OFDM symbols, as shown in FIGS. 23 to 27, each block A (indicated by diagonal lines) refers to a resource region with which a CRS (Cell-specific Reference Signal) is likely to be transmitted, each block B (indicated by dense dots) refers to a DMRS (DeModulation Reference Signal) region, each block C (indicated by sparse dots) refers to a region with which a PDCCH (Physical Downlink Control CHannel) is likely to be transmitted, and each block D (indicated by a blank) refers to a region with which the CSI-RS is likely to be arranged. In the exemplary arrangements shown in FIGS. 23 to 27, up to three cells can be multiplexed with four antenna ports.
In Pattern 1 shown in FIG. 23, the CSI-RSs from a 0-th antenna port to a 3rd antenna port are transmitted with OFDM symbol #4, the CSI-RSs from a 4th antenna port to a 7th antenna port are transmitted with OFDM symbol #11. In Pattern 2 shown in FIG. 24, the CSI-RSs from a 0-th antenna port to a 3rd antenna port are transmitted with OFDM symbol #4, the CSI-RSs from a 4th antenna port to a 7th antenna port are transmitted with OFDM symbol #11. In Pattern 3 shown in FIG. 25, the CSI-RSs from a 0-th antenna port to a 3rd antenna port are transmitted with OFDM symbol #4, and the CSI-RSs from a 4th antenna port to a 7th antenna port are transmitted with OFDM symbol #11.
Further, in Pattern 4 shown in FIG. 26, the CSI-RSs from a 0-th antenna port to a 3rd antenna port are transmitted with OFDM symbol #5, the CSI-RSs from a 4th antenna port to a 7th antenna port are transmitted with OFDM symbol #12. Likewise, in Pattern 5 shown in FIG. 27, the CSI-RSs from a 0-th antenna port to a 3rd antenna port are transmitted with OFDM symbol #5, the CSI-RSs from a 4th antenna port to a 7th antenna port are transmitted with OFDM symbol #12.